[fedora-virt] Multicast on qemu-kvm?

James Hubbard jameshubbard at gmail.com
Tue Sep 22 14:09:38 UTC 2009

2009/9/22 Ján ONDREJ (SAL) <ondrejj at salstar.sk>:
> On Tue, Sep 22, 2009 at 08:16:54AM -0400, James Hubbard wrote:
>> I've noticed that multicast apps don't seem to work with qemu-kvm
>> using a windows guest.  Anyone know the reason?
> Mutlicast (SAP + video stream) works well for me on qemu-kvm 0.10.92-4.fc11
> (f11+virt_preview). May be you are using wrong networking type, my qemu is
> configured to use bridged networking. May be user networking can't forward
> multicast packets.
>                SAL

(This time to the list.)

We are using bridged networking.  We'll do some more testing and I'll
report what I find.  My biggest concern is the large number of
multicast groups and how it impacts the guests.  It's possible that
some of the apps may subscribe to more than 2000 multicast groups
depending on their current state.   The amount of data being sent can
be especially high as well.  I wouldn't expect the apps to be running
on guests in the high data rate situation, but it would be nice to be
able to test with a large number of groups passing a moderate amount
of data.

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